142 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



accurate analyses of fogs from some country town of say 50,000 

 inhabitants, in which manufacturies are not carried on, for 

 comparison with similar analyses from the metropolis. 



II. Extent of the London Fog Area. — I have been at great 

 pains to ascertain how far the London fog-cloud extends around 

 the metropolis. In this I have had the most cordial co-operation 

 of our nurserymen and cultivators, who have supplied me with 

 detailed information as to the times of occurrence of fogs, and as 

 to the nature and extent of the injuries sustained. In many 

 cases I have availed myself of the opportunity to visit their 

 collections, and form an estimate of the damage done, valuable 

 for purposes of comparison. The extent of the fogs is greatest 

 in a westerly and south-westerly direction, and has been traced 

 as far as 35 miles away westward, and 25 miles south-west, 

 under special atmospheric conditions. Exceptionally the 

 London fogs are met with at even 50 miles distance on this 

 side. With the wind in an easterly or north-easterly direction, 

 these outlying districts receive visitations of fog with the 

 accompaniments of sooty deposits and sulphurous smell. No 

 doubt the concentration is not so considerable, nor the duration 

 so long, as nearer London, but it is sufficient to at once affect 

 the buds and flowers of such sensitive Orchids as Lcelia anceps, 

 Cattleya TriancB, Calantlic, &c. The effect of the fog on foliage 

 at these distances is, fortunately, small, though in certain in- 

 stances it is sufficient to destroy the seedlings of Cucurbitas, 

 Tomatoes, &c, which are extremely sensitive. As one follows 

 the effects of fog down the Thames Valley, from the most out- 

 lying stations affected, to London, the observed effects increase 

 in severity, till they are indistinguishable from those noted at 

 stations actually within the metropolis. At Kew, for instance, 

 the destruction has been most disheartening, it having come to 

 flowers, flower-buds, and foliage alike. Effects of similar nature, 

 but less in total magnitude, are reported from spots five miles 

 further west. Southwards, the North Downs afford a valuable 

 barrier, which in many cases would seem to filter off the more 

 deleterious constituents of the fog. Indeed, the configuration 

 of the country and the nature of the sub-soil have an important 

 influence in determining the immunity of a given locality 

 from damage. Eastwards I have information as to damage 

 from so great a distance as Maidstone, over 30 miles. Since, 



